Adhesives based on block copolymer rubbers have found wide-spread use in nonwoven construction applications, e.g., disposable absorbent articles such as diapers, feminine hygiene articles, and adult incontinence devices. These products are typically applied at temperatures above 130° C. and often above 150° C. Lowering the application temperature of adhesives used in the manufacture of such products below 120° C. would improve the thermal aging in application equipment and reduce issues with heat sensitive or lighter basis weight substrates. However, in order to apply the adhesive below 120° C. using current application technology the viscosity must be low enough to spray and extrude cleanly. To lower viscosity, lower molecular weight polymers and higher levels of diluent have been used at the expense of performance. These approaches result in lower mechanical strength and more importantly less resistance to flow at high temperature. While the use of waxes to act as diluents as well as crystalline reinforcing agents is known, this approach suffers from a reduction in the effective open time the adhesive is capable of forming adequate bonds in the laminating processes used to make disposable articles.
There is thus a need for a hot melt adhesive that can be applied at low temperature, i.e., below about 120° C., which has adequate open time for bonding and has a high resistance to flow at elevated temperatures. Such attributes would make the adhesives particularly well-suited for use in the manufacture of disposable articles. The invention fulfills this need.